Polarization is a property of electromagnetic waves, such as light, that describes the orientation of oscillations. When light propagates in free space, it generally propagates as a transversal wave having a polarization perpendicular to the direction of travel of the light wave. When light is reflected at shallow angles, the light wave is typically polarized to some degree, which often increases glare.
Polarization filters can be used to convert a beam of light having undefined or mixed polarization into a beam of light having well-defined polarization. Such polarization filters can be used to improve image capture, to enhance vision, and to improve the performance of vision algorithms for segmentation, shape and motion estimation. For example, polarization filters are often used to separate between diffuse reflection and specular reflection. See S. K. Nayar et al., “Separation of Reflection Components Using Color and Polarization”, International Journal of Computer Vision Volume 21, Issue 3 (1997), Y. Y. Schechner et al., “Polarization-based Vision Through Haze”, Applied Optics 42, No. 3, 51-525 (2003), and Y. Y. Schechner et al., “Recovery of Underwater Visibility and Structure by Polarization Analysis”, IEEE Journal of Oceanic Engineering, 30, 3, 570-587 (2005).